Conventionally, an organic electroluminescent element having a plurality of light-emitting units, i.e., having a multi-unit structure, is known.
For example, with an organic EL element described in Patent Document 1, a plurality of light-emitting units exhibiting organic EL light emission are connected in series, and a portion or all of the light-emitting surfaces of the plurality of light-emitting units are stacked to form a light-emitting surface. In addition, the plurality of light-emitting units include light-emitting units exhibiting at least two or more different luminescent colors, the light-emitting units exhibiting at least one color are formed in multiple layers to obtain a desired mixed color that is a composite of the different luminescent colors from the light-emitting surfaces.
Also, an organic electroluminescent element described in Patent Document 2 includes at least one first light-emitting unit including a plurality of organic light-emitting layers that are stacked, and at least one second light-emitting unit including an organic light-emitting layer having a single layer structure. In addition, the light-emitting units are sandwiched between an anode and a cathode in a state of being stacked with a connection layer therebetween for supplying an electrical charge to the light-emitting units.